DictionaryAI

sentinel

SEN-ti-nuhl/ˈsɛn.tɪ.nəl/

Pluralsentinels

7 meanings of sentinel

Practice

  1. 1
    guard (person)nouncountable
    A guard posted to keep watch; a sentry.

    Two sentinels stood at the palace gates, rifles on their shoulders.

    The camp posted a sentinel on the ridge to warn of anyone approaching.

    UsageOften stand sentinel or post a sentinel; in everyday use, sentry or guard is more common.

    Similarsentry, guard, lookout, watchman

    Note

    It once named the watch as well as the watcher: Francis Bacon advises that princes "keep due sentinel," and Macaulay's sentinels pace the ramparts. Today it has a formal, often literary ring, while sentry is the everyday military word.

  2. 2
    health warningnounbefore a noun
    In medicine and epidemiology, used before a noun for something that signals a health risk, such as a disease or an adverse effect.

    Health officials keep flocks of sentinel chickens to detect mosquito-borne viruses early.

    A cluster of rare cancers among factory workers can be a sentinel event pointing to a workplace hazard.

    Note

    The word works almost only before another noun, naming the early-warning parts of disease surveillance. Sentinel animals, such as flocks of chickens, pick up an infection, often before people do; sentinel clinics report cases from a sample of the population; and a sentinel event is a single case rare or serious enough to point to a wider problem.

    Checked 1 Nov 2026 · 3 facts

    • Sentinel animals, including chicken flocks, acquire infections and can provide warning before human cases occur. cdc.gov
    • Sentinel clinics report cases drawn from a subset of the population. who.int
    • A sentinel health event can be an individual case whose occurrence warns of an underlying problem warranting investigation. stacks.cdc.gov
  3. 3
    lowest ranknounobsolete
    A private soldier; a soldier of the lowest rank.
    “I will not permit the poorest centinel to be treated with injustice.”
    1789, John Moore, Zeluco
    Note

    An obsolete use that names a rank rather than a post: the common soldier, as distinct from the guard on watch. Eighteenth-century writers could spell it centinel, as John Moore does in Zeluco, where a speaker vows not to let "the poorest centinel" be treated with injustice. In older military writing, a sentinel need not be standing guard at all.

    Checked 1 Nov 2026 · 4 facts

    • An obsolete sense denotes a private soldier rather than specifically a guard on watch. en.wiktionary.org
    • John Moore's eighteenth-century novel Zeluco uses the spelling 'centinel' in the quoted phrase. en.wiktionary.org
    • A fictional speaker promises not to allow even the poorest centinel to suffer injustice. upload.wikimedia.org
    • The historical soldier sense does not require the person to be standing guard. en.wiktionary.org

Practice

Can you tell the meanings of sentinel apart? Answer 3 quick questions from this page, or write your own sentence and AI will check it.

Origin

Recorded from the 1570s, from Middle French sentinelle, from Old Italian sentinella (perhaps through the idea of "perceive, watch"; compare Italian sentire, "to feel, hear, smell"), probably from Latin sentiō ("to feel, perceive by the senses"). It is probably related to sense and sentient.

Checked 1 Nov 2026 · 8 facts